This invention relates to dunnage bag and particularly to a composite bag having an inner bladder and and outer mesh.
Products are commonly shipped as stacks of cargo on pallets placed in the cargo space of an enclosure such as a truck trailer or container. After placing the cargo in the cargo space, it is generally necessary to support the cargo in the cargo space to prevent damage due to shifting
Common practice is to position two rows of cargo on pallets, each row extending from the front to the rear of the container. The space between the rows should contain braces to prevent shifting as described above.
xe2x80x9cDunnage bagsxe2x80x9d, large inflatable bags made of paper with an air tight plastic liner, have been used to prevent the shifting of cargo during transportation. These bags are placed in the space between the cargo and the walls of the container or between neighboring rows of pallets holding cargo and then inflated. The bags are typically inflated to a pressure of not more than 1xc2xd to 2 pounds per square inch (psi). When the cargo arrives at its destination and prior to unloading, the bags are punctured and discarded.
The problem of damage to cargo during transport has such a commonality and severity that the American Association of Rail Roads has adopted standardized requirements for an acceptable protection system.
These requirements for dunnage bags include an xe2x80x9c80% footprintxe2x80x9d: where a footprint is the area of contact of the interface between the wall of the cargo and the bag. This specification satisfies the two requirements that the interface of the bag exert sufficient force over a broad area of the bag to support the product without crushing the cargo such as when the cargo might be bags of fruit.
The A.A.R.R. has also developed a uniform testing procedure that any shipping system must pass in order that the participating company receive the required approval from that Association to apply that system as a basis for its shipping procedure.
The test, referred to herein as the AARR test, incorporated by reference into this specification, is described as follows:
1. A first railcar, loaded with 45,000 pounds, is positioned on a railroad track.
2. Additional railcars having a total weight of 275,000 pounds are accelerated to a speed of 3 miles per hour and caused to slam into the first car.
3. This procedure is repeated a total of 3 times at speeds of 6 miles per hour each time.
4. The spacers are examined to determine any damage that has occurred to the spacers such as rupture of dunnage bags, etc. The amount of movement is measured to determine the effetiveness of the air bags.
Various embodiments of dunnage bags have been disclosed for addressing requirements of dunnage bags.
U.S. Pat. No. 3,427,995 to Stafford discloses an inflatable dunnage bag system positioned between cargo and the end bulkheads of railroad cars. This disclosure does not address the problem of filling space between rows of pallets parallel to the track.
U.S. Pat. No. 4,136,788 discloses a dunnage bag made of layers of paper with flaps extending from the ends of the ply joined to the other wall. This invention suitable only where large overall thickness is required for extra protection. and the xe2x80x9cpinched end of the bag results in diminished contact (footprint) can be tolerated.
U.S. Pat. No. 4,553,887 to Reeves discloses a dunnage bag made of triangular sheets of kraft paper lined with polyethylene.
U.S. Pat. No. 4,591,519 to Liebel discloses an airbag for bracing made of a stiff paperboard having good vertical stiffness when uninflated.
U.S. Pat. No. 5,042,663 to Heinrick discloses joinable inflatable bladders for packaging.
U.S. Pat. No. 5,288,188 to Vanes discloses a dunnage bag constructed of welded rectangular sheets.
U.S. Pat. No. 5,372,396 to Nahmen discloses a cargo bed liner with side panels pivotally attached.
U.S. Pat. No. 5,431,525 to Sansone et al discloses a dual air bladder air bag.
U.S. Pat. No. 5,693,163 to Hoover et al discloses a method for making inflated dunnage bags xe2x80x9con sitexe2x80x9d including unrolling a folded sheet and sealing step.
U.S. Pat. Nos. 5,868,534 and 5,788,438 to Boshorn et al discloses a sealed bag inserted into a paper tube.
U.S. Pat. No. 5,908,275 to Howlett discloses an inflatable bag comprising an inflatable inner bladder surrounded by a pair of paper plies.
None of the systems dunnage bags (inflated to 3 psi disclosed in the prior art perform satisfactorily when subject to the test sanctioned by the AARR when the space between the parallel pallets is greater than 12 inches. This is because, of a number of reasons including swelling of the bag toward the ceiling and because, when the space is greater than 12 inches, an attempt to inflate the bag up to the 3 psi limit results in the bag not having enough surface area coverage and therefore not exerting enough force on the product.
Accordingly, the present practice for filling spaces having widths greater than twelve inches, is to occupy the additional space with xe2x80x9cfillersxe2x80x9d. Sheets of xe2x80x9choney combxe2x80x9d panel are commonly used for such purposes. However, the use of filler panels presents a number of inconveniences including storage of the panel when not in use and the inconvenience associated with installing and removing the filler panels when loading and unloading the cargo space and extremely high cost of the fillers.
Rigid collapsible braces have been disclosed for supporting cargo in cargo space. For example, U.S. Pat. No. 4,236,854 discloses a brace having side rails and extensible side arms
U.S. Pat. No. 4,473,31 to Wisecarver discloses a foot assembly and extensible element with lever locking member.
U.S. Pat. No. 5,181,815 to Haberkorn discloses a collapsible bracing structure and rotatable latches for releasing.
U.S. Pat. No. 3,665,638 to James discloses a load brace with selectable fixed positions.
In view of the above, there continues to be intense interest in improving the dunnage bags and systems presently on the market and disclosed above in terms of reducing expense and inconvenience for filling space between rows of pallets with product where the vertical walls of cargo are spaced by more than twelve inches .
It is an object of this invention to provide a dunnage bag for filling spaces between a pallet loaded with cargo and a neighboring pallet loaded with cargo.
It is a further object to provide a bag that protects cargo on pallets during transit when the the space between rows of cargo on pallets is greater than 12 inches without the use of additional void fillers. In this situation, it is also an object that the bag surpasses the requirement of the A.A. R. R. rest for dunnage systems that protect cargo on pallets for transit
These requirements include developing a footprint of at least 80% when the bags are inflated to 1-3 pounds per square inch pressure.
This invention is directed toward a composite bag comprising an inflatable bag enclosed inside an outer mesh bag. The inner bag comprises polypropylene sheet material about 0.10 mm thick especially formulated to have enhanced elasticity . The mesh comprises woven polypropylene. In use, the bag is positioned in the space between a pair of pallets, each loaded with cargo. The inner bag is inflated to fill the space and support the bag during transit.
The inner polyethylene sheet material is sufficiently thin and flexible to enable the inner bag to stretch without rupturing to the limit imposed by the mesh and contact 80% of the vertical cargo surface.
In a typical situation, the composite bag is inflated to 1xc2xd psi. The area of the double bag facing the ceiling of the container is contained by the mesh so that bulging toward the ceiling of the container is minimal.
For spaces between stacks of cargo that are greater than 12 inches, use of the composite bag of this invention in place of the xe2x80x9cstandardxe2x80x9d bag together with filler panels provides greater convenience and reduced cost for preventing shifting of cargo during transportation.
Each bag typically has an inlet valve adapted for admitting air into the bag from a pneumatic pump and a separate nipple with a cap wherein the nipple is large enough such that, when the cap is removed, the air is expelled very quickly allowing quick and convenient deflation of the bag prior to unloading the cargo.